Party-line telephone system.



H. J. ROBERTS, G. A. SOANS & A. H. GRAVES.-

' PARTY LINE TELEPHONE SYSTEM;

urmommn 111.21) mm. a, 1907.

CW4. a

Patented June 29,1909. 'ZSHEIJTS-SHEET 1.

E o-{II H. J. ROBERTS, G. A. SOANSG A. H. GRAVES. PABTYLINE TELEPHONE SYSTEM.

7 APPLICATION FILED JAILB, 1907. 926,510, I 1 Patented June29, 1909.

2 SHEETS-SHEET 2.

UNITED STATES PATENI.

FFICE;

HOME-R J. ROBERTS, OF EVANSTON, AND O YRIL A. SCANS-AND ALBERT H. GRAVES, OF

CHICAGO, ILLINOIS, ASSIGNORS, BY MESNE ASSIGNMENTS, TO HOMER ROBERTS TELE- PHONE GO., A CORPORATION OF WEST VIRGINIA.

PARTY-LINE TELEPHONE SYSTEM.

Specification of Letters'iatent.

Patented June 29, 1909.

Application filed January ,8, 1907. Serial No. 351,296.

Inited States, residingat Chicago, in said- Cook county, Illinois, have invented certain new and useful Improvements in'Party-Line Telephone Systems, of which the following is a specification.

This invention relates to improvements in party-line telephone systems, and refers more specifically to a selective lock-out system of the bridgingltype in which ringers responsive to differentiated current. are effective to control the talking connections.

"Among the salient objects of the invention are to provide a system in which the ordinary bridging method of arranging the line wires may be employed in conjunction with sub'stations embodying both selective signalingand lock-out or privacy connections; to provide in such a system lock-out connections at each sub-station controlled by a corresponding relay which is in turn controlled by the operation of the ringer or other signaling device, whereby the simple operation of throwing that particular kind of current upon the line eiiective to operate the ringer of the particular station wanted, automatically operates the relay of that station and cuts in the party wanted; to provide in a system of the general character described means whereby the simple act of signaling for a connection on the part of the subscriber operates to lock out all other parties on the same line; to provide in such a system means enabling the locked out subscribers to at all times send in an emergency calling signal; to provide a system so organized that the subscribers stations are each moreparties on the same line can be given:

talking connections to the exclusion of all otherpa-rties and in which also the restoring 0f the entire line to normal is accomplished by a single operation whether one or more parties have been given talking connections;

to provide a system" of the character described which embodies independent calling in and clearing out signal systems; to provide a system in which the talking circuits are full metallic and free from external grounds: to provide a system particularly adapted to common battery practice, although, in its broader sense, not limited to this type; to provide a system characterized by extreme simplicity of manipulation, both on the pa rt of the exchange operator and the subscribers, and therefore susceptible of being handled with great rapidity; to provide a system so organized that the several substations are 1n no sense interdependent; to

, provide a specific embodiment of the system in which harmonic ringers are employed; to

provide a system so organized that it is impossible for a subscriber to tie up the line or interfere with the exchange operators manipulationof the same without deliberately disorganizing his set; and in general to provide a simple and practical system of the character referred to.

To the above ends the invention consists in the matters hereinafter, described, and more particularly pointed out in the appended claims.

In theaccompanying drawingsFigure 1 is a view showing diagrammatically the central exchange and sub-station apparatus and circuit connections; Fig. 2 is an elevation of the'lock-out relay; Fig. 3 is a top plan view of the savine with a portion of the biasing bar broken away; Fig. 4 a sectional detail of the contact'group of the lock-out relay; Fig. 5 an elevation of the harmonic ringer, parts being broken away, and Fig. 6 a top view of the ringer, with partsbroken away.

The preferred embodiment of the system shown herein is one in which harmonic ringers are employed at the several sub-stations, responsive, as usual, to alternating current of different frequencies, and these ringers are bridged across the line, but, as intimated in. the-statement of the objects ofthe invention, the systemis not limited to this specific embodiment.

Describing first the circuits and apparatus as they-are shown conventionally in the diagram-pea and 'B, respective1y,'designate as a halves of the cord circuit'and associated apparatus. Associated with the calling end of the cord circuit are a plurality of ke s, as

1, 2, 3, 4, one corresponding to each su -sta- 5 tion, and these keys in turn control corre-- sponding devices, 5, 6, 7 and 8, affording the several difierent frequencies of current required; the devices shown in this instance being alternators. Associated with each end of the cord is also a restoring key, as 9 and 10. There is also connected with the cord an operators listening key 11 and a diflt'erentially wound signal relay 12. Other accessories of the central exchange will be describedin connection with the description of the circuits.

Describing now more particularly the substation apparatus and circuits, 1t is to be noted that all sub-stations are precisely alike,

with the exception that the several ringers are, of course, so modified in the usual way as to respond only to current 'of proper frequency. In the diagram 13 designates as a whole the ringer, the windings of which are bridged across the drop wires L and R, as usual. Mounted upon a vibrating part of the ringer, the armature as shown is a contact device 14v connected by conductor 15 with drop wire R. A coiiperating back contact 16 is connected'by a conductor 17 with the switch spring 19 of a lock-out relay designated as a whole 18. This relay is in its general construction similar to an ordinary polarized magnet comprising the usual spools 20, 20', coiiperating armature 88, bi-

asing bar 87, and frame work (not shown in the diagram). Upon the frame work mounted a spring latch 23 (hereinafter ore specifically described) which normally holds the switch spring 19 depressed and in contact with a bottom spring '24; the latter being connected with one side of the receiver 25 by a conductor 26. When released from the latchthe switch spring rises and closes contact with a top spring27 which is connected by a conductor 28 with drop wire R. Switch spring 19 is also connected by a conductor 29 with a cam spring 30 which is actuated mechanically by the switch-hook 31 and said switch hook serves to momentarily force spring 30 into contact with a spring 30 connectedto ground at 32; Normally the switch-hook rests in engagement with a ounding spring 33connected to ground as indicated at 34. As the switch-hook rises, upon removal of the receiver therefrom, it leaves spring 33 and closes witha top sprin 34 hereconnected by a conductor 35 throng the transmitter 36 to drop wire L and momentarily establishes a flash ground circuit through .the relay18 and to a corres'pon ground at central. This circuit is as to lows: From ground at 32, through springs 30' and 30, conductor 29,'windings of the re- 5 lay 18 connected with conductor 29, thence by a conductor 37 to switch-hook, to spring 34, conductor 35, left drop wire L, left main line L, and to and through line relay D. Describing the circuits of the latter inst-rument, a conductor 38 permanently connected with L leads to a bottom spring 39 of the relay, which spring normally engages the center or switch spring 40 thereof. The latter is connected by a conductor 41 with a back spring 42 normally closed'upon and coopcrating with a contact 43 carrying but insulated from the tip spring 44 of the spring jack. Spring 43 is connected by a conductor 45 with the windings of relay D, and the latter by a conductor 46 with one side of a battery 47. The opposite side of this battery is grounded, as indicated at 48.

The circuit from L through 38, '39, 40, 41, 42, 43, 45, and the windings of the relay and battery to ground completes the flash ground circuit from the sub-station, and closes the relay D, and at the same time operates the lock-out relay to trip off the latch spring 23 thereof; the latter effect being accomplished by a cam extension upon the end of the armature 88 engaging the inclined overhanging part 23' of the latch spring, as more fully described in connection with the description .of the construction of said relay hereinafter to follow. The operation of relay D and lock-out relay 18 accomplishes three distinct ends, ,viz: The relay D disconnects the battery 47 from the line and lights a signal lamp, and the relay 1S establishes ta king connections at the subscribers set. The opening of circuit between 39 and 40 at relay D disconnects the battery from line and at the same time establishes a holding circuit between switch spring 40 and the top spring 49 which is connected by a con du ctor 50 through a signal lamp 51 to the grounded side of the battery. Thisholding circuit is maintained until the operator plugs in, whereupon the movement of tip spring 44 opens said circuit between contacts 42 and 43.

The talking circuit connections established by the operation of relay 18 are from drop wire L over conductor'35, through transmitter 36, spring 34, switch-hook 31, conductor 37. to a branch conductor 52, condenser 53,

to one side of the. receiver 25, and from the latter'by a conductor 54 to conductor 17, from the latter through switch spring 19, top spring 27 and conductor 28 to drop wire R It will be noted that normally the receiver is short circuited, but that upon the movement of switch spring out of engagement with bottom spring 24 this short circuit is opened.

After relay D has operated and before central has plugged in, it is obviously impossible for any other subscriber to secure a talking connection'for the reason that there is no battery on the line by meansof. 130

which his lock-outrelay vcould tripped.

miliar to those skilled in this art, being connected between a pair of split repeating I coils 57, 57', and one side of the battery, the positive, being 58; Vith battery be seen that a flash ground established at any other station than that of the party grounded, as indicated at 55 to line, it will having talking connections, will induce a flow through his lock-out relay in a directionopposite that, which is required to trip it otll: That is to say, the flow will I befrom ground '32 at his station by way of conductor 23 through his lock-out relay by way of his switch hook connections to left main line over the latter to the metallic bridge then tXI'StlIlgfll the subscrlbers set. who has been glven talking connections,

through the latters set including switch hook connections and the look-out relay at that stat-ion (current through the latter relay being in the proper directionto keep ittripped otl') to the right main wire and thence to the sleeve side of the cord circuit, to and through battery and to ground 58. The attempt to secure connection will therefore be ineffective, However, the circuit last described is made use of to transmit a calling in si nal to central so that the operator may be apprised of the fact that another subscriber desires connection, and may, if she so desires, take the line away from the busy party and makesuch connection. This is accomplished through the differential relay 12. This relay comprises a magnet having two windings wound oppositely upon the same core, as indicated in the diagram, each winding being included in the corresponding sideof the cord circuit.

The armature of the magnet operates to close a lamp circuit at two contact springs 59 and (30; said lamp circuit being connected to the opposite sides of battery 55 and including a lamp 61, as shown clearly-in the diagram. Current flowing over one side of the line only, as it does in the case of the flash ground circuit described, obviously operates relay l2 and momentarily lights the lamp. If "it be understood that the repeated moving of the switch-hook up and down indicates" an emergency call, it will be obvious that-the IBSulllflIlt flashing of the lamp at central would induce the operator to give the desired connection. In this connection it may be noted that when the subscriber who has talking connections finishes his conversation and .rethrns his receiver to the switch-hook, by so doing he places a continuous ground upon the llne through the bottom spring 33 and this causes the lamp 61 to glow continuously and so forms a clearing out signal. 'This last circuit is from ground t 34, through spring 33, switch-hook 31, conductor 37, windings of relay 18, switch spring 19, top spring 27,,conductor 28, drop wire R and thence to central over right main line. It will be noted that the current tlowthrough the subscribers relay 18 is in a opposite end E of the cord and then closes that one of the ringing keys, 1, 2, 3 or 4, corresponding to the party desired, thereby throwing on ringing current from the corresponding alternator and selectively ringing the called partys bell. The metallic circuit which effects the ringing is the usual and obvious circuit, and need not be t'aced, it being noted, however, that the ringing is effected in this instance, as is often done, through a condenser 62 at the sub-station.

The ringing of a subscribers bell closes a circuit through his relay which trips the latch of the latter and ives him talking connections as follows: I. pen a vibrating part. of each ringer, the armature as shown in the present instance, is mounted a yieldable spring contact 14, connected to the right drop wire by conductor 15, as hereinbefore mentioned. Upon the frame of the ringer is mounted a stationary but adjustable contact screw 16 which coiiperates with the tip of spring 1% and is connected to switch spring 1%) by conductor 17, as already described. These contacts are so adjusted as to close only when the ringer is thrown into full vibration and the clapper thereof actually makes contact with the gongs, thereby avoiding the closing of the circuit controlled by these contacts by the false or semi-vibrations common to harmonic ringers.

Connected with one side of the calling end of the cord, at central, is a grounded battcry (33, the connection being through a conductor (34 having branch wircs (E5, (3G, (37 and battery 63 through the corresponding lockout relay at the sub-station being called; this circuit being from ground at battery 63 over the sleeve or right side of the cord and over I the right main wire and corresponding drop wire to contact spring 14, thence over conductor 17, to and through the relay, and by conductor 37 to the switch-hook and to ground through the bottom spring 33. These intermittent current impulses 0 rate the armature of the relay and trip 0 the latch, as hereinbefore described. In this-connection it may be noted that the intermittent impulses, though extremely brief, are effective for the reason that the armatu e of the look-out relay is unrestrained in that movement. which trips the latch until it encounters the latter, and the momentum of the armature is effective in disengaging the latch even with the highest rate of frequency now used in harmonic ringing. Moreover, it will be noted that the higher the rate of frequency the more certalnly will the successive impulses increasethe momentum of the armature to do the necessary \vork, while as to the lower frequencies the interval of contact is long enough to insure effective operation by a sin 1e contact. The talking connections estab ished by thus ringing on are, of course, the same as those hereinbefore described as secured by the calling in subscriber. It will be noted that battery 63 has that pole thereof to line which is opposite in polarity to the battery which operates the relay over the left limb, and hence operates the relay in the right direction.

Emergency signals and clearin out signals are sent in from the line with which the calling end of the cord is connected in precisely the same manner as in the case of the line with which the answerin end is connected, and for this purpose t e relay 12' is interposed in this end of the cord and controls a lamp circuit including a lamp 61 arranged in precisely the same relations to battery 55 as is the lamp 61 and its circuit. Occasionally it is necessary, of course, to put two or more parties upon the same line in talking connection with each other. This is accomplished by first taking the order of the party who calls in and thereby automatically secures talking connections, then Withdrawing the answering plugand inserting the calling plug, and proceeding to select the called party precisely as though he were upon another line. It is to be noted that the calling party must be instructed-to momentarily hang up his receiver while the wanted party is being rung on in case such party be upon the same llne with himself. This precludes any disarranging flow of current through the calling partys station.

To restore the lines to normal the two clearing keys 9 and 10 are interposed in the respective ends of the cord circuit and control a battery 73 which is desirably of somewhat higher voltage than the other batteries described, to insure an ample flow of current notwithstanding several sub-stations may be bridged on, i. e., have been given talking connections, so as to restore simultaneously. The negative side of battery 73 is grounded at 74 and this side of the battery connected by conductors 75, 75', with normally open springs on the tip sides of the res ective restoring keys 9 and 10. Similarly the positive pole of the battery is connected by conductors 76 and76' to the open springs of the restoring keys at the sleeve sides thereof. Accordingly when either key 9 or 10 is closed, and assuming that the party or parties having talking connections have returned their receivers to their switchhooks, simultaneous metallic and ground to ground circuits are established which flow through the look-out relays in the proper direction to latch them up or restore them to normal. At the exchange end, these circuits are obvious. At an given sub-station the grounded circuit will be from the right drop wire over conductor 28, sprin 27 and 19, conductor 17, through the win ings of the relay, conductor 37, switch-hook 31, spring 33 and ground 34:. The mechanismof the relay is so organized that the circuit through its contact springs 27 and 19 is maintained until the relay becomes deenergized. Should any part who .34, switch-hook 31, conductor 37, windings of the relay, conductor 17 switch spring 19, top spring 27 and conductor 28 to the right drop Wire and is of the proper polarity to restore the relay. This latter circuit is, of course, the circuit utilizedto take the line away from an arbitrary or careless subscriber who attempts to hold the line too long or ne lects to hang up the receiver after he is done talking.

V The two main instruments at each substation, viz: the ringer and the relay will now be described: The ringer is a wellknown make of harmonic instrument, bein a polarized instrument having the usual hee piece 77, biasing bar 78 connected with the heel piece, and at its opposite end bearing against a pair of iron or steel blocks 79 clamped between the two members 80, 80, of the yoke and in turn clamping and holding a flat leaf spring 81 upon which the armature 82 and clapper-stem 83 are suspended. Each clapper-stem carries a clapper-weight 84 of adjusted Weight corresponding to the frequency it is intended to respond to. Upon one of the spool heads is mounted switch and circuit connections between the aibracket 85 through which is adjustably threaded the contact screw 16 referred to responding end of the armature is mounted the insulated yielding spring 18 is also a polarized ma net having the usual heel piece 86, biasing therewith and overhanging the armature 88, yoke 89 mounted upon the spools and carrying the armature, and the grou of three springs, 19, 24 and 27, herein efore de scribed.

The armature is provided with a right angled arm or extension 90 which overlies the group of springs, and in this extension is inserted an insulating bushing 91, in which in turn is mounted a head in 92. The head of the bushing projectsslightly below the armature that engages the top spring (see detail F ig. 4:). The head of the pin 92, in

the upstroke of the armature, engages the inclined portion 23 of the spring latch 23 and forces outwardly the latter. This spring latch is mounted upon a downturned extention 89 of the yoke and insulated from the latter. Below the inclined latch lip 23 is formed a stop lip 23 which projects outwardly -beyond the latch lip and forms a stop to arrest the downward movement of the switch spring under the action of the armature. The purpose of this stop is to prevent sparking and consequent momentary interruption of the circuit between the top spring and switch spring during the latching movement. An insulating spacing bushing 93 is mounted in the bottom sfpring'27, extends through an opening in the switch spring andengages the top spring. The tension of the bottom spring is upward, and when the group is unlatched insures the closing of contact between the bottom and switch ,springs.

We claim as our invention: 1. In a party line telephone system, the combination with a line wire extending through a plurality of substations, means for sending differentiated current over said line wire and a selectively responsive ringer at each 5 substation, of a lock out relay at each subringer and relay of each substation, wherestation, contact mechanism actuated and controlled by said relay, talking circuit con nections including said contact mechanism,

and controlling connections between the by the operation of the relay is controlled through the ringer.

2. In a party-line telephone system, the combination with a line wire extending through a plurality of sub-stations, means for sending differentiated current over said line wire and a selectively-res onsive ringer at each sub-station, of a 100 -out relay at each sub-station, talking-circuit connections controlled by said relay, a manually operable switch and relay ofeach sub-station, where by the operation of the switch controls the operation of the-lock-out relay.

3. In a party-line telephone system, the

14. The relay, combination with a line wire extending hrough a plurality of sub-stations, means bar 87 conne d 9 for sending differentiated current over said line wire, and a selectively-responsive ringer at each sub-station, of a lock-out relay at each sub st-ation, contact mechanism actuated and controlled bysaid relay, talking circuit connectionsincluding said contact mechanism and electrical contacts and suitable circuit connections between the ringer and relay of each sub-station, whereb the operation of the ringer controls and initiates the operation of the relay.

4. In a party-line telephone system, the combination with a line wire extending through a plurality of sub-stations, means for sending differentiated current over said line wire, and a selectively-responsive ringer at each sub-station, of a polarized lock-out relay at each sub-station, talkin -circuit connections controlled by said re ay, and electrical contacts and suitable circuit conneclions between the ringer and relay of each sub-station, whereby the operation of the ringer controls and initiates the operation of the relay.

5. In a party-line telephone system, the combination with a pair of line wires .extending through a lurality of sub-stations, means for sending differentiated current over said line wires, and a' selectively-responsive ringer at each. sub-station, of a lock-out relay at each sub-station, talking-circuit connections controlled by said relay, electrical contacts and suitable circuitconnections between the ringer and relay of each sub-station, and means for establishin' simultane-s tion, means for establishing a metallic cur- 4 cuit alternating current flow through said ringer, and a ground to ground current flow through saidrelay.

7. In a party-line telephone system, the combination with a line wire extending through a plurality of sub-stations, means for' sending differentiated current over said line wire, and a harmonic ringer at each sub-station, of a lock-out mechanism at each sub-station, talking-circuit connections controlled thereby, and operative connections between the harmonic ringer, and lock-out mechanism whereby the latter is controlled through the former.

8. n a party-line telephone system, the combination with a pair of line wires extending through a plurality of sub-stations, cans for sending alternating currents of different frequency over said line wires, and a harmonic ringer at each sub-station, of a lock-out relay at each sub-station, talkingcircuit connections controlled by said relay, a pair of contacts carried by the ringer, one moving with the vibrating part of the ringer and the other relatively stationary and ar-' ranged in cooperative relation with the vibrating contact, circuit connections extending from one of the line wires through said contacts, through said relay and to ground means for grounding the line at central, and a source of current interposed in said grounded circuit.

HOMER J. ROBERTS. CYRIL A. SOANS. ALBERT H. GRAVES.

Witnesses:

FRANK L. BELKNAP, EMILIE ROSE. 

